With the rapid development of semiconductor technologies, semiconductor devices have been developed toward higher integration level, and higher speed. The effective lengths of the gate structures of the semiconductor devices have become smaller and smaller. Such an effective length reduction of the gate structures reduces the control ability of the gate structures on the channel regions of transistors.
The gate structure of a fin field-effect transistor (FinFET) forms a fin-shaped and branched three-dimensional (3D) structure. One or more fins protruding from the channel region of the FinFET is formed on a substrate. The gate structure covers the side and top surfaces of the one or more fins. Thus, inversion layers are formed on the two sides of the channel region; and the FinFET can be controlled to be on/off from two sides. Such a design increases the control ability of the gate structure on the channel region; and is able to better reduce the short channel effect.
However, the semiconductor structures formed by the existing techniques still have less control ability on the channel region, but with large leakage current. The disclosed device structures and methods are directed to solve one or more problems set forth above and other problems in the art.